"I agree with the underlying tenets of your post, but a few points I would put forth:
The PR industry is far from dead. In fact, the top 10 global agencies brought in well over $1B last year, and spending on PR actually increased last year. Early-stage companies write off traditional PR and agencies at their own peril, even in a rapidly changing media environment.
Social media is not a ‘silver bullet’ approach to promoting a small business, and I don’t believe it ever will be. Having said that, you are absolutely correct – an astute entrepreneur can get pretty far on their own if they go about it the right way.
“PR agencies of the past will have a hard time adapting…” You are absolutely right. The majority of today’s top PR agencies operate according to an outdated paradigm and business model, and the industry is ripe for the right entrepreneur to erode a sizable portion of their business.